THE EFFECT OF TEMPERATURE IN THE MASS ON THE CHEMICAL COMPOSITION OF SILAGE

The effect of temperature on silage quality was investigated in a series of trials over a period of three years.
The results indicated that when conditions in the silage were favourable for the formation of lactic acid, either through treatment or because of the herbage itself, low temperatures in the mass had no adverse effect on silage quality.
Some results suggest that, with chopped or lacerated silage, low maximum temperatures are associated with better quality silage. The results, however, were not entirely consistent.
There appeared to be little or no advantage in allowing unchopped silage to heat to 100°F.     

THE INTAKE OF HAY AND SILAGE BY COWS

Three comparisons were made, with non-lactating fistulated cows, of the voluntary intake of silage and hay prepared from similar herbage. On average 28% more dry matter was eaten as hay than as silage. Silage and hay had similar digestibilities, but silage residues tended to remain in the gut longer than those of hay. The amount of digesta in the reticulo-rumen immediately after a meal ad lib . was greater with hay than with silage. The cows spent longer eating and ruminating per kg dry matter of silage than of hay. The results are discussed in relation to possible factors determining the voluntary intake of silage.     

THE EFFECT OF FERTILIZER NITROGEN ON SILAGE FERMENTATION

Direct-cut grass which has been heavily fertilized often produces silage with a poor fermentation. An investigation was carried out to study the effect of rate and timing of N applications to herbage intended for direct-cut silage. A small but consistent increase in silage pH was recorded after high levels of N were applied 7–8 weeks before cutting. The application of additional N fertilizer 10–14 days before cutting the sward had an adverse effect on silage fermentation. Changes in herbage composition following different levels of applied N are outlined.     

THE USE OF SODIUM METABISULPHITE IN SILAGE MAKING

Three trials in which metabisulphite was used as a silage additive are described and the results discussed.
The data from two small-scale trials suggests that metabisulphite and molasses each have a similar effect on the quality of the silage produced, and that wilting appeared to be more effective than either of these two additives.
A comparison of silages in two large-scale trials indicates the necessity for uniform distribution of the metabisulphite.     

SELF-FEEDING OF SILAGE

Self-feeding of silage has been successfully practised at Tillycorthie for 5 years. With unrestricted access to the feeding face, daily grazing times for 9-cwt. animals varied from 4 periods totalling 121 minutes in the case of stronger animals to 7 periods totalling 378 minutes.
In feeding, chopped silage was more wasteful than long silage. The daily intake of 7-cwt. animals was 68 lb. of silage and 4 lb. of oat straw. The labour requirement for 70 animals was 6–6 hours per week.
Food and labour costs on the system were 10 s . 11 d . per week. The estimated cost of the same items on. turnips and straw feeding is 16 s . 4 d . per week.
The health of the cattle was good and growth excellent, and the animals went out to graze in a condition which allowed them to make maximum liveweight gain on grass.     

THE EFFECT OF LEVEL OF PROTEIN IN SILAGE ON THE INTAKE AND PRODUCTION OF DAIRY COWS

Two silages of contrasting protein content were compared in a 16-week winter-feeding experiment with 12 Ayrshire cows. One silage contained 8.2% DCP in its DM and the other 15.9% DCP. The silages were fed ad lib . with a supplement of either barley or barley plus groundnut cake. The DM digestibilities of the low and high protein silages were 74 and 67%, respectively, and the calculated S.E.s 56 and 47. Silage and total DM intakes were highest in the treatments containing low protein silage and in those containing groundnut. The mean daily milk yields for the treatments with and without groundnut were 35.4 and 32.s5 Ib (16.1 and 14.8 kg), respectively, with the high-protein silage, and 38.1 and 35.0 Ib (17.3 and 15.9 kg) with the low-protein silage. The S.N.F. contents of the milk were low and averaged 8.26 and 8.34% on the high- and low-protein silage treatments, respectively, and were not affected significantly by the supplements. It is concluded that the low-protein silage was superior to the high-protein silage as a feed for cows, and that the digestibility of the silage DM was a truer indication of quality than protein content.     

THE ESTIMATION OF FEED INTAKE BY SHEEP ON A SILAGE DIET

The results of nineteen digestibility trials with sheep on different silages have been reported. From these data and from the results of forty trials with sheep carried out by Watson (15) it has been shown that Lancaster's method of calculating feed intake (9) can be applied to silages when the crude protein content is within the range studied (9–24% of the dry matter). For silages in this category, no advantage has been found in taking the nitrogen content of the silage dry matter into account in calculating feed intake.
The digestibility of crude protein and Lancaster's'constant'have both been correlated with the crude protein content of the silage dry matter for the fifty-nine trials considered (r = 0.767 and r = 0.452 respectively). Although it has been found unnecessary to take the protein content of silage into account in calculating dry matter intake when feeds containing 9.24% crude protein in the dry matter are used, evidence is presented which indicates that this factor is of considerable importance when herbage of low protein content is fed. The equation, which has been derived from the silage data considered, has been found to be valid when compared with the results of trials with fresh herbage and well preserved hays of low protein content.
The results of this work indicate that Lancaster's method is a suitable one for estimating the feed intake of animals engaged in self feeding of silage, provided the silage has been well preserved.     

THE EFFECT OF LENGTH OF SILAGE ON ITS VOLUNTARY INTAKE BY CATTLE

Trials are described in which the intake of silage of varying length was determined. The results indicate that a higher voluntary dry-matter intake occurred as the length of the silage became progressively shorter, but this effect appeared to diminish when the silages were supplemented with concentrates. Data from one trial indicate that reducing the length of hay had no effect on voluntary intake when concentrates were fed.     

THE POTENTIAL VALUE OF SILAGE EFFLUENT AS A FERTILIZER

Results of the analysis for dry-matter, nitrogen and major base content of 9 silage effluents obtained from farm silos and 3 effluents from experimental tower silos are presented. The mean values obtained for the principal plant nutrients in the 12 effluents examined were 0·19% N, 0·037% P and 0·38% K. The results indicate that effluents may be a useful source of plant nutrients, particularly when undiluted with rainwater, and that, in general, silage effluents appear to be superior to liquid manure in manurial value.     

FACTORS AFFECTING THE VOLUNTARY INTAKE OF SILAGE AND HAY

Experiments with cows and sheep are described in which the voluntary intakes of hay and silage of differing digestibility were determined. The voluntary intake of hay increased consistently with increasing digestibility, but the relationship was not as well defined for silage. The addition of concentrates depressed the intake of hay, and this effect was more marked for hay with a high digestibility than with poorer quality hay. Concentrates appeared to depress the intake of hay by sheep more than by cows, an effect which was again more marked when the hay had a high digestibility value.     

THE INFLUENCE OF SUPPLEMENTS OF FLAKED MAIZE ON THE DIGESTIBILITY BY STEERS OF SILAGE, FRESH LUCERNE AND LUCERNE HAY

Three experiments examine the effects of giving small supplements of flaked maize to steers on the digestibility and retention of nutrients from rations of grass silage, lucerne hay and fresh lucerne. The digestibility of the dry matter, crude fibre and crude protein of the silage ration was depressed by the successive additions of 1, 2 or 3 Ib flaked maize per day. There was a tendency for the steers to retain more nitrogen as the level of starch supplementation increased, in spite of a lowered crude-protein digestibility. The digestibilities of the constituents of lucerne hay and fresh lucerne were slightly increased by the addition of 2 and 4 Ib flaked maize per day. The reasons are discussed for the different effect of the supplemental starch on the digestibility of the crude fibre from grass silage and from fresh or cured lucerne. Attention is drawn to the increase in the retention of N following the supplementation of silage with starch.     

THE EFFECT OF TYPE OF CONCENTRATE ON MILK PRODUCTION WHEN SILAGE IS THE ONLY ROUGHAGE OFFERED TO COWS

Trials are described in which barley was compared with a concentrate containing barley and groundnut cake, both concentrates being used to supplement silage. An increase in milk yield was obtained when the compound concentrate was given to the cows, which may be attributable to an inadequate supply of protein in the silage/barley ration or to the effect of supplementary protein on silage intake.     

THE USE OF PROPIONIC ACID AS AN ADDITIVE FOR MAIZE SILAGE

Two clamps of maize silage were prepared in mid-October, one with 0·33% propionic acid applied during harvesting and one without additive. The treated silage had a peak temperature 3°C below that of the untreated silage. The estimated loss of DM during ensiling was 8% greater in the untreated silage. The stability and acceptability of the silages were tested after exposure to air. The treated silage was slightly more stable than the untreated milage and the intakes by heifers were sligbtly greater. The digestibilities of the two silages estimated in wether sheep were similar, averaging 68·6% digestible OM in the DM at maintenance level and 63·5% at a high level of feeding. The intakes and growth rates of calves and beifers oifered the two silages were also similar.     

THE EFFECT OF HISTAMINE ON SILAGE DRY-MATTER INTAKE

The oral introduction of 0·5 g histamine as the diphosphate into the rumen of sheep produced no effect on the physiological condition of the animals. The feeding of histamine, as the dihydrochloride, in levels up to 1 g/day to sheep on silage diets did not affect the dry-matter intake.     

THE USE OF BARN-DRIED HAY AND SILAGE IN FATTENING YOUNG BEEF CATTLE

A series of trials was carried out in which barn-dried hay and silage were fed to young fattening cattle with or without supplementary barley. Liveweight-gains on silage and barn-dried hay alone were too low to provide an adequate finish during winter feeding. Liveweight-gains on hay alone were always higher than those obtained on silage alone, the difference being more marked in lighter animals. There was a marked response to supplements of 3 and 4 lb (1.4 and 1.8 kg) of barley, the response being significantly greater in silage-fed cattle than in those fed on barn-dried hay. There was some evidence of growth compensation with the introduction of a barley supplement to cattle on silage diets, but there was no such response in those fed on hay. Compensatory growth was not accompanied by improved digestibility or N retention.     

THE GENERAL PATTERN IN SILAGE FERMENTATION IN TWO SUBTROPICAL GRASSES

Three sets of previously-published experiments have been re-analysed by numerical methods intended for the elucidation of pattern in sequential data. The results suggest that for Setaria sphacelata cv. Nandi and Chloris gayana cv. Samford Rhodes the stable terminal silage to be expected under subtropical conditions is not the high lactic-acid silage of temperate regions, but a silage with a relatively high proportion of acetic acid. Lactic-acid silage is formed, but usually behaves as though in a transitional phase. However, silage made from mature Setaria can be maintained in the lactic-acid phase by the addition of high percentages of sugar. The silage fermentation can sometimes be retarded, or deflected into an undesirable path for reasons that are not understood.
The above patterns suggest three hypotheses for more fundamental investigation. First, since acetic-acid silage can be expected under most subtropical conditions, its properties require careful investigation. Secondly, relatively young Setaria may be regarded as a source of acetic-acid silage, but the optimum amount of sugar to be added for ensiling more mature grass needs investigation. Thirdly there is an urgent need to investigate the causes of retardation of fermentation, and of its deflection into an undesirable path, because until these causes are understood, the outcome of ensilage will remain uncertain.     

THE EFFECT ON FATTENING STEERS OF SUPPLEMENTING SILAGE WITH DRIED GRASS OR ROLLED BARLEY

Eighteen crossbred Aberdeen-Angus and six Shorthorn steers with an average liveweight of 382 kg were given silage (DM content 22.3%) ad lib., supplemented with 0, 1.2, 2.4 and 3.6 kg artificially dried grass, or 1.8 kg rolled barley, per day. A digestibility study carried out on the silage and dried grass showed that the concentration of the metabolizable energy was 52.7 and 45.6 kcal/100 kcal of food, respectively. Live-weight gain increased with each level of supplementation. Supplementation did not significantly affect the intake of silage DM, but differences in the intake of total DM were significant. The killing-out percentages of the steers were similar. The results suggest that dried grass pellets may be a usefid supplement for a silage diet. It was shown that 1.12 kg of dried grass was equivalent to 1.80 kg rolled barley as a supplement for silage.     

A COMPARISON OF SILAGE AND BARN-DRIED HAY FOR BEEF PRODUCTION

Three trials were carried out to compare the feeding value of silage and barn-dried hay for fattening bullocks of approximately 8 cwt initial body weight. In each case the silage and hay were cut from the same sward at the same time. In the first trial the bullocks fed on hay gained 1·88 lb/day while those self-fed on silage gained 1·55 lb/day during a 70-day feeding period. In the second trial of 70 days, the bullocks fed on hay gained 1·96 lb/day and those fed on silage from a trough gained 2·39 lb/day. In the third trial, individually-fed bullocks housed in stalls and given the same hay and silage as used in Trial 2 gained 123 lb/day on hay and 127 lb/day on silage. The significance of these results is discussed in relation to the findings of other workers.     

SILAGE AND MILK PRODUCTION. A COMPARISON BETWEEN BARLEY AND DRIED GRASS AS SUPPLEMENTS TO SILAGE OF HIGH DIGESTIBILITY

Grass silage made in late May from S23 perennial ryegrass was offered to 14 Ayrshire cows in a 16–week winter-feeding experiment. The silage had a DM content of 23.2% and contained 16–8% CP and 70.4% digestible organic matter in the DM. The silage was fed ad lib. as the sole feed in the control treatment, and supplemented with either barley or higuality dried grass cubes at the rate of 2, 3 and 4 kg/10 kg milk (2, 3 and 4 Ib/gal) in the other 6 treatments. The daily intake of silage DM was 11.6 kg/cow (25.6 lb) in the control, and significantly less in the supplement treatments. Silage intakes were higher in the dried grass than in the barley treatments. The mean daily yields of milk were 14.5 kg.cow (32.0 lb) in the control, 15.7, 16.6 and 17.0 kg (34.6.36.6 and 37.5 lb) in the barley treatments, and 17.8, 20.2 and 19.8 kg (39.2, 44.5 and 43.6 lb) in the drierass treatments, at the 2, 3 and 4 kg rates of feeding, respectively. The solidoat (SNF) content of the milk was lowest in the control treatment and highest in the drierass treatments. It is concluded that grass silage of high digestibility could be made successfully on a farm scale and that, with such a silage, a supplement of higuality dried grass was superior to a supplement of barley for milk production.     

THE GROWTH OF BEEF CATTLE FED ON MAIZE SILAGE SUPPLEMENTED WITH DRIED LUCERNE, FISHMEAL OR UREA

Two experiments are reported in which 119 steers were fed ad lib. on maize silage, supplemented with different proportions of dried lucerne. In addition, the effect of including white fishmeal with the silage at levels up to 13% of the total diet was studied in one experiment. In another, the effect of adding urea to the silage (at 0.9% of the DM) was investigated. In hoth experiments the response in liveweight gain to increasing amounts of lucerne was curvilinear. The highest mean level of daily gain (1.5 kg/head per day) in the first experiment was achieved when the diet contained 62% lucerne or 13% fishmeal. In the second experiment the highest mean daily gain (1.1 kg/head per day) was achieved when the diet contained 71% lucerne. Daily liveweight gains were simOar for the cattle fed 25% of the diet as lucerne with sQage to which urea had heen added, and for those fed higher proportions of lucerne with untreated silage.